Age and heat stress as determinants of telomere length in a long-lived fish, the Siberian sturgeon.
Résumé
Telomeres shorten at each cell division due to the “end-replication problem”, but also in response to oxidative stress. Consequently telomeres shorten with age in many endotherms, and this shortening is accelerated under stressful environmental conditions. Data in ectotherm vertebrates remain scarce so far, so our goal was to review existing data for fish, and to test the influence of age and stress on telomere length in a very long-lived fish, the Siberian sturgeon (Acipenser baerii). Our review of the literature revealed age-related telomere shortening in approximately half of the published studies. In the Siberian sturgeon, we found a significant telomere shortening with age, both at the intra-individual level using red blood cells (-12.5% in 16 months) and at the inter-individual level using cross-sectional samples of fin over an age-range of 8 years. We also found that heat stress (30°C) significantly reduced telomere length by 15.0% after only 1 month of exposure. Our results highlight that both age and stressful environmental conditions might be important determinants of telomere length in fish.